Method of producing a fibrous product from extruded organic thermoplastic filaments



1953 R. c: HARRINGTON, JR.. ETAL 3,1 METHOD OF PRODUCING A FIBROUSPRODUCT FROM EXTRUDED ORGANIC THERMOPLASTIC FILAMENTS Filed Sept. 9,1960 Robert GHaningM James L. Smi th Jalnes H.130 nd INV EN TORS' cwmmmATTORNEY}? United States Patent Jersey Filed Sept. 9, 1960, Ser. No.545929 4 Claims. (Cl. 156.2)

This invention relates to a process for the manufacture of fibrousarticles. More particularly, it relates to a process for convertingfibro-pl-astic material directly into fibrous material suitable forsmoking devices such as cigars and cigarettes, non-woven fabrics, cablestuillng, and the like.

The manufacture of fibrous material and products requires many complexsteps. For example, paper for filters prepared in the conventionalmanner requires the steps of pulping, screening, drying and taking up ona roll. The paper is then crimped and split to the proper width andfinally processed into filters. Cellulose ester filters are prepared byesterifying cellulose, dissolving in acetone, filtering the solution andspinning by the conventional dry spinning technique. Continuousfilaments formed into tow in this manner or by a similar lengthy processfrom po-lyolefins or other fiber-forming substances are then orimped andbaled. In making the filters, the tow is opened; that is, the filamentsare spread apart. Then a bonding agent is *added, and the tow is passedinto a garniture, a conventional cigarette-making machine. Sometimesvarious additives such as rice starch or carbon particles are used inpaper and cellulose acetate filters to increase the surface area. Thestrong fibers required for use in non-woven articles, tows, webs,filters, and such formed from polymer solutions by prior art processesusing various types of spray equipment have been collected in a numberof difierent ways, for example, on a moving belt, on a preformedcontinuous rope or yarn, or a rotating card. In many cases, electricallycharged plates have also bee-n necessary. As yet, no method has beendevised whereby all of these complicated intervening steps can becompletely eliminated so that wrapped or crimped fibrous products suchas filters and the like can be produced directly from melts or solutionsof the various polymers which can be used.

It is accordingly an object of this invention to provide a continuousprocess for the manufacture of filters from a polymer melt or solution.

It is another object of this invention to provide a process which ismore economical and simpler than the multistep processes now employed inthe manufacture of fibrous products.

It is also an object of this invention to provide a process for themanutfacture of filters from. more economical materials than thosepresently employed.

It is another object of this invention to provide a process whereby veryfine filamentous material can be processed directly into filters andother fibrous products.

It is still another object to provide a process which will convertfilaments with little resilience into a filter firm enough for use as acigarette tip.

It is a further object of this invention to provide a simple,substantially one-step method of producing a continuous tow or web froma plastic polymer.

It is a still further object of this invention to provide a process forthe collection of continuous tows of sprayed fibers of various diametersand lengths useful in filters, non-woven fabrics, cable stuffing, andthe like and prepared directly from a molten polymer or polymersolution.

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These and other objects of this invention will be apparent from thedescription and claims which follow.

We have found surprisingly that a polymer melt or solution coming from astorage tank or other appropriate container can be directly convertedinto fibers which can then be either 1) continuously formed into tow andtaken up continuously or which can be (2) collected and boundimmediately in a garniture into a filter useful on a cigarette or cigaror other smoking device. This continuous operation is carried out byapplying a stream of inert gas or steam propelled substantially at rightangles to the melt or solution issuing from the supply container at avelocity and under a pressure suificient to attenuate the melt orsolution into the fonm of fibers.

If it is desired to form the fibers directly into tow, the tow iscollected in a direction substantially countercurrent to that of thepropellant stream on a guide and take-up rolls. A belt or cord or othersimilar means for providing an initial collecting point for the fiberscanbe used, but such an arrangement is not an essential part of thisinvention. A particularly suprising feature is the fact thatsubstantially all of the freshly formed fibers find and adhere to thepreformed tow. Although we do not know exactly why this happens, wetheorize that such an arrangement of a propellant spray andcountercu-rrent collection causes the formation of an air stream orblanket upon which the preformed tow rests. Once the tow starts to form,the take-up roll is started (the belt or cord or other similar means forproviding an initial collecting point for the fibers, if used, beingimmediately removed from the system) and the tow continues to form in acontinuous manner. It is collected in a suitable manner, for example, ina convenient receptacle or on one or more spools. The temperature of thepropellant stream, its velocity and pressure should be adjusted so thatthe freshly formed fibers are still in the plastic state when they areformed into tow in order to adhere at the point of contact and produce acontinuous filament.

The uses for tows and webs formed in accordance with' this proceduresare many and varied. Cigarette filters, air and liquid filters and thelike are illustrative of such. Tows formed from thermoplastic materialscan be cut into uniform lengths on conventional textile processingequipment, blended with other fibers such as viscose and cotton, andformed into non-woven articles. Such tows and webs are also useful aspacking or stufiing material and as decorative materials.

If, on the other hand, it is desired to convert the fibrous materialdirectly into a final fibrous product, the arrangement can be altered sothat the attenuated fibers formed by the propellant stream directedagainst the polymer melt or solution coming from the storage containerand directed thereagainst at right angles are sprayed directly into afunnel, the narrow end of which connects with a specially arranged airaspirator. The fibers pass through the aspirator and on into a shortmultiperforate tube which extends into the horn of a garniture or otherbinding mechanism. The exhaust end of the aspirator terminates at apoint close to the beginning of the short multiperforate tube. Theexhaust air is dissipated through the multiperforate tube holes. Paperor other packaging material can be passed through a narrow slot betweenthe exhaust end of the air aspirator and the rnultiperforate tube andthence through the tube along the lower side thereof into the garniturehorn. This modification of the process is especially advantageous forthe utlization of very short fibers, viz, less than about two inches.

It can thus be seen that by this particular procedure filaments can beprepareddirectly from the molten polymer or polymer solution andconveniently collected immediately thereafter in an appropriate wrappingor pressing device. The fibrous product can be a filter rod suitable forattaching to the tobacco portion of cigar, cigarette or other smokingdevice.

We have found that any plastic fiber-forming polymer, particularly thepolyolefins and cellulose esters, are suitable for processing inaccordance with this invention. Representative polyolefins which areespecially appropriate are polyethylene and polypropylene. Celluloseacetate, cellulose acetate propionate, and cellulose acetate butyrateare illustrative of the cellulose esters.

Various modifications of the above-described process can be made, forexample, where the fibers are formed directly into a very large tow, bator wide web of fibers. A header can be used to supply the polymer meltto the propellant stream and a wide web formed in this manner. On theother hand, the propellant streams can be caused to converge to producea more cylindrical tow. Several difierent polymers can be supplied fromseveral sources to form a blended tow and the fiber size controlled bythe techniques of varying the polymer-propellant fiow ratio. Variousfluids such as air, steam, nitrogen or carbon dioxide, for example, canbe used as the propellant with polymers such as the polyolefins, nylon,polyesters and cellulose esters such as cellulose acetate propionate.Actually, any fiber-forming material amenable to being sprayed can beused in this process. We prefer to use thermoplastic polymers such aspolyolefins and cellulose esters with and without plasticizers forspraying.

The materials which can be sprayed to give the fine fibers for whichthis particular invention is especially adapted are quite varied.Although we prefer to use materials which can be sprayed from a melt,materials sprayed from a solution employing a volatile solvent can alsobe used.

When the fibers are formed directly into a fibrous prod net inaccordance with the alternate procedure given above, the amount ofcompressed air used on the air aspirator and the garniture speed may beadjusted in accordance with the requirements of the type of fibers to beproduced and the specific properties of the filter cigarettes or othersmoking devices prepared.

The process of this invention may be more readily understood from thefollowing description and drawings which illustrate certain preferredembodiments thereof.

FIG. 1 is a diagrammatic representation of an embodiment wherein apolymer melt or solution is converted directly into rod-like fibers bythe application thereto at right angles of a propellant stream and thefibers formed into tow, which is collected on take-up rolls.

FIG. 2 is a diagrammatic representation of an alternative embodiment ofthis invention wherein the fibers are produced in accordance with thesame procedure as that illustrated in FIG. 1 but are collected in afunnel-aspirator device and conveyed directly to a garniture whereinthey are assembled as a final fibrous article.

Looking first at FIG. 1, a polymer melt issues from container into apropellant stream supplied from propellant nozzle 12. String-like fibers14 formed by attenuation follow the propellant stream until they forminto continuous tow 16 which is carried away by way of a plurality ofguides 18, leading to take-up rolls 20 and 22 between which it passes.The tow is collected in a direction countercurrent to that of thepropellant flow.

In the alternative embodiment shown in FIG. 2, the polymer melt fromcontainer 10 is formed into fibers 14 as in FIG. 1 by a propellantstream from propellant nozzle 12. The fibers now in string-shapedfilament form are drawn through a funnel 24 by an aspirator 26 to whichair or other appropriate inert gas or fluid is provided through line 28and from which it is withdrawn through orifice 30. The filaments passthrough multiperforate .tube 32, to which multiperforate tube 32 paperis supplied at point 36 from roll 34 into garniture horn 38 and thenceinto garniture 40, in which the final bound product is formed.

The following examples are illustrative of our invention, which is to belimited only by the appended claims.

Example 1 Fibrous tow was formed as in Example 1 with the ex ceptionthat the molten polyethylene was at a temperature of C. and the size ofthe filaments was in the range of 3-10 denier per filament.

Example 3 Fibrous tow was formed as in Example 2 with the exception thata 15-pound air propellant stream was used and the filaments producedranged in size from about 8-30 denier per filament.

Example 4 A stream of molten polyethylene such as that used in Example1, except that the temperature thereof was 190 C. instead of 140 C. wasintroduced to a 50-pound steam propellant stream directed at rightangles thereto, and the tow collected theretrom consisted of fibershaving a size or from 0.5 to 5 denier per filament.

Example 5 Polyethylene having a density of 0.925 and an inherentviscosity at 300 F. of approximately 1000 centipoises was melted andintroduced at 275 C. to a propellant stream of 50% steam directed atright angles thereto, and a tow consisting of fibers in the 3-20 denierper filament range was collected on take-up rolls such as thoseillustrated in FIG. 1.

Example 6 Fibrous tow was formed as in Example 1 except thatpolypropylene having a density of 0.91 and a viscosity at 320 C. ofapproximately 5,000 centipoises was used instead of the polyethylene.

Example 7 A stream of plasticized, molten cellulose acetate propionate/z-second propionate) was introduced to a 32- pound steam propellantstream in a manner illustrated by FIG. 1 to produce semi-continuousfilaments in the range of about 100 denier per filament. The filamentswere collected to form a continuous tow.

Example 8 Continuous tow was formed as in Example 7 with the exceptionthat the plasticized molten cellulose acetate propionate was introducedto a 20-pound air stream at C.

Example 9 Continuous tow was formed as in Example 7 with the exceptionthat cellulose acetate was used instead of cellulose acetate propionate.

Example 10 Continuous tow was formed as in Example 7 with the exceptionthat cellulose acetate butyrate was used instead of cellulose acetatepropionate.

Example 11 In this example numerical references are to FIG. 2 of thedrawing. A low molecular weight polyethylene having a specific gravityof 0.907 and a viscosity at 300 F. of approximately 9,000 centipoiseswas melted in a blow case 10 with 75 pounds of steam in the case. Avalve in the bottom of the case was opened and a stream of the moltenmaterial /s in diameter was caused to fiow from a short piece of tubing.A stream of compressed air ejected from a A tube 12 was directed at aright angle to the stream of molten material and in the direction of thefunnel 24. Filaments varying from about /2 to 5 denier were blown intothe funnel. An air dofler 26 stufled the filaments into a multiperforatetube 32 and on into a garniture 40 where they were wrapped with paperand converted into a tubular filter.

Example 12 A filter was prepared according to the procedure of Example11 except that polypropylene having a specific gravity of .91 and aviscosity at 320 C. of approximately 5,000 centipoises was used insteadof the polyethylene.

Example 13 A filter was formed in accordance with the procedure ofExample 11 with the exception that cellulose acetate propionate was thepolymer used.

Example 14 A filter was prepared as in Example 11 except that celluloseacetate was used instead of the polyethylene.

Example 15 The procedure of Example 11 was used to prepare a tubularfilter, cellulose acetate butyrate being used in place of thepolyethylene.

The following example is given to show the surprising and unobviousimportance of drawing the filaments through the multiperforate tubebefore allowing them to enter the garniture horn when being formeddirectly into filters.

Example 16 The process of Example 11 was followed with the exceptionthat the multiperforate tube was removed, the aspirator leading directlyinto the garniture horn. After a few minutes of operation, the filamentsbegan to jam in the garniture in such a manner that no filters could beproduced.

These examples serve to show only a few of the many variations possiblein this process. Many changes can be made to give any desired towconsisting of any reasonable fiber size at either low or high rates ofproduction. The examples show only sprayed fibers formed from polymermelts, but solvent solutions can also be use-d. When solvents are used,a solvent recovery system should be used.

It can readily be seen that We have provided a method whereby a moltenpolymer or a polymer solution may be directly converted by theimpingement thereon at right angles of a propellant stream directly intofibrous tow or a fibrous product. To form a continuous tow, the fibersare withdrawn from a stream of fibers substantially countercurrent tothe stream. This substantially countercurrent collection of tow is oneof the features of this invention. When it is desired to form thefilaments directly into a bound product such as a filter, they are drawnby means of an aspirator through a multiperforate tube which serves toallow excess compressed air to be dissipated evenly through theatmosphere and flius prevents clogging in the horn of the garniture intowhich they are conveyed for forming into the final product. Without thepresence of the multiperforaite tube, a plug of fibers is formed whichwill pass on through the garniture and prevent the formation of thedesired product.

We theorize that the reason for this is that the air is caused to turnand blow out of the mouth of the aspirator and thus prevent theincreases in pressure necessary to force the fibers into the garniture.

Another feature of this invention is that the denier of the filamentsformed by :our process is practically unlimited. As illustrated by thepreceding examples, filaments varying all the way from /2 to 20 deniercan be collected. A particular advantage is the capability of our Theutility of the pnocess of this invention is manifold.

It can be used in forming fibrous material for twisting to make a cordor yarn, crimping and cutting into staple yarn, winding on frames formulti-shaped filters, or passing into the horn of a garniture inpreparing filter rods.

Although the invention has been described in detail with reference topreferred embodiments thereof, it will be understood that variations andmodification can be effected within the spirit and scope of theinvention as described hereinabove and as defined by the appendedclaims.

We claim:

1. A process for producing a fibrous product from an organicthermoplastic substance which comprises extruding in a generallydownward direction a molten flow of thermoplastic substance, attenuatingsaid molten flow into a plurality of stringshaped fibers by directing acontinuous stream of steam under pressure at approximately right anglesto said molten flow, supporting said fibers only by said stream ofsteam, collecting said plurality of steam supported fibers in anelongated zone on a plane substantially horizontal with said stream ofsteam to form a tow of substantially parallel discontinuous filamentsand withdrawing said tow at an angle to said zone and in a directioncounter to the direction of said stream of steam.

2. A process for producing a fibrous product from an organicthermoplastic substance which comprises extruding in a generallydownward direction a molten flow of said substance, directing acontinuous stream of steam at an abrupt angle to said molten flow undersuflicient pressure to propel said molten fiow and attenuate the flowinto a plurality of string-shaped fibers, supporting the attenuatedfibers only by said stream of steam, collecting said plurality of steamsupported fibers in an elongated zone as a web of tow of substantiallyhorizontally aligned discontinuous filaments and withdrawing said tow atan angle to said zone and in a direction counter to the direction ofsaid stream of steam.

3. A process for producing a fibrous product from an organicthermoplastic substance selected from the group consisting ofpolyethylene and polypropylene which comprises extruding in a generallydownward direction a molten flow of said substance, attenuating saidmolten flow into a plurality of string-shaped fibers by directing acontinuous stream of fluid under pressure at approximately right anglesto said molten flow, supporting said fibers only by said stream offluid, collecting said plurality of fluid supported fibers in anelongated zone on a plane substantially horizontal with said stream offluid as a tow of adhering substantially horizontally aligned filamentsof 0.5 to 20 denier per filament and withdrawing said tow at an angle tosaid zone and in a direction counter to the direction of said stream offluid.

4. A method for the treatment of organic thermoplastic material whichcomprises:

(1) directing a fluid stream substantially at a right angle to adownwardly moving flow of molten extruded organic thermoplastic materialthereby attenuating said material into fibers moving in substantiallythe same direction as that of said fluid stream,

(2) collecting by air aspiration the attenuated fibers in substantiallyhorizontally aligned adhering form while under the propelling influenceof said fluid as a continuous web of tow made up of discontinuousfilaments varying in denier from 0.5 to 20 and ILA) References Citefi inthe file of this patent UNITED STATES PATENTS Tay1or Apr. 30, 1946Manning June 12, 1956 8 Manning June 12, 1956 Crawford et a1. June 4,1957 MacI-Ienry Nov. 12, 1957 Frickert et a1. May 15, 1959 Crawford et-al Aug. 25, 1959 Manning June 21, 1960 Miller July 19, 1960

1. A PROCESS FOR PRODUCING A FIBROUS PRODUCT FROM AN ORGANICTHERMOPLASTIC SUBSTANCE WHICH COMPRISES EXTRUDING IN A GENERALLYDOWNWARD DIRECTION A MOLTEN FLOW OF THERMOPLASTIC SUBSTANCE, ATTENUATINGSAID MOLTEN FLOW INTO A PLURALITY OF STRING-SHAPED FIBERS BY DIRECTING ACONTINUOUS STREAM OF STEAM UNDER PRESSURE AT APPROXIMATELY RIGHT ANGLESTO SAID MOLTEN FLOW, SUPPORTING SAID FIBERS ONLY BY SAID STREAM OFSTEAM, COLLECTING SAID PLURALITY OF STEAM SUPPORTED FIBERS IN ANELONGATED ZONE ON A PLANE SUBSTANTIALLY HORIZONTAL WITH SAID STREAM OFSTEAM TO FORM A TOW OF SUBSTANTIALLY PARALLEL DISCONTINUOUS FILAMENTSAND WITHDRAWING SAID TOW AT AN ANGLE TO SAID ZONE AND IN A DIRECTIONCOUNTER TO THE DIRECTION OF SAID STREAM OF STEAM.